Maker Pro
Maker Pro

Re: lateral mosfets vs. bjts in audio amplifier design

K

Kevin Aylward

Jan said:
I am not sure, frequency response is different from a non-linear
curve. If the amp is linear then you get no mixing products,
even if the freq response is not flat in that area.
Or am I missing something here?

Yes...Its a practical issue.

Its essentially impossible to design an amplifier with low 20khz/19khz IMD
that doesn't have an enormous BW. Its automatic, that standard conventional
power amps with low IMD at HF, have wide BW. This is because it needs lots
of feedback at HF, which means a very large unity loop gain frequency.

If one has a power amp, and it can *only* achieve a power BW of 20khz,
assuming no deliberate filters, than its IMD will be dreadful,
err...probably.

And please, no comments on the 0.001% of all product sold with only local
feedback no loop feedback, sort of stuff. I am discussing mainstream amps.

Kevin Aylward
www.kevinaylward.co.uk
www.blonddee.co.uk
www.anasoft.co.uk - SuperSpice
 
R

Rich Grise

On Thu, 23 Oct 2008 19:27:50 GMT, "Kevin Aylward"


Slightly relevant, and mildly humorous:

On page 45-14 of the 1972 "Reference Data for Radio Engineers" is a table
of random digits which is identical in each book.

Maybe they assumed that each customer would only need one copy of the book? ;-)

And really, putting a different chart in each copy would be prohibitively
expensive.

Cheers!
Rich
 
R

Robert Latest

John said:
"Pro" audio design seems like an infinite chain of stolen circuits.

Most important bit in "pro" audio is that it won't break under almost
any circumstances, especially on-stage in live situations.

The basic circuit topography is not so important - the older the
better.

robert
 
K

Kevin Aylward

John said:
Random fiddling is a perfectly valid way to find new circuit
topologies. I do that all the time. Sometimes one has a hunch that
some circuit may exist, somewhere in circuit-space, and fiddles until
it emerges.

Yes...

However, the brain rejects most of the fiddles before it even reaches our
consciousness, maybe millions of variations, such that it gives the illusion
that the ones that actually emerge are not fundamentally based on the
Darwinian machine algorithm.

Chemists only get to use 90-ish elements. Musicians mostly use the
same list of notes. Novelists use the same character set. But new
stuff happens.

Yes new stuff can happen, but only if we assume that quantum randomness
kicks in somewhere in the brain, otherwise, its all classical mechanics,
like the current position and momentum determines the next.

If Bohmian Mechanics, is correct, then nothing is new.

Kevin Aylward
www.kevinaylward.co.uk
www.blonddee.co.uk
www.anasoft.co.uk - SuperSpice
 
R

Rich Grise

Yes new stuff can happen, but only if we assume that quantum randomness
kicks in somewhere in the brain, otherwise, its all classical mechanics,
like the current position and momentum determines the next.

You're denying Free Will. "quantum randomness" is a term used by
"sciencists" to rationalize away the fact that everything has Free Will.
If Bohmian Mechanics, is correct, then nothing is new.

Well, evidently, it's not.

Hope This Helps!
Rich
 
J

JosephKK

No, just simply answer the question,
maybe I can use your input to improve the code.
Maybe not....

If you need to boost a frequency band, this eats into dynamic range.
Most people rather live with the "suck out". While most audiophiles
don't even like tone controls, it is somewhat accepted that you can
filter out a peak in a room and it is not the end of the world.
Unless you use remez to generate a linear phase filter, any attempt to
equalize will alter group delay.

It's actually more complicated than this if the room isn't designed to
be well diffused. This is because music is not a sine wave. Given how
the sound bounces off the surfaces, it is possible that a short burst
would need different equalization than a sine wave. In fact, that is
how pseudo anechoic testing is done.

It's really harder to design a good room than a good amplifier. There
are room simulators. Not exactly what the pros use, but you can buy
CARA and simulate room acoustics.
http://www.rhintek.com
 
K

Kevin Aylward

John said:
---
I agree.

The thrill of "Eureka!" certainly seems to be more than just
incremental plodding toward a solution which emerges from the soup,
but Kevin's postulations are well founded in that whatever we build
we build upon the shoulders of our forbears.

There had to have been, however, something which started it all off.

Actually no. there is no reason that there should be any reason for
anything. Some in physics are taking the view that the mass-energy just
appeared, from nowhere.

Physics is characterised by "The laws of physics". However, these laws can
only exist, presumably, if mass-energy exists. In a truly empty universe,
there can not be any laws that prohit anything. Therefor, in an empty
univese here is no reason why mass-energy cannot simple appear from nowhere


I favour this position, as I see no other reasonable alternative. When all
else is proven false, what remains must be answer..

Kevin Aylward

www.kevinaylward.co.uk
 
K

Kevin Aylward

Rich said:
You're denying Free Will.
Indeed.

"quantum randomness" is a term used by
"sciencists" to rationalize away the fact that everything has Free
Will.

Not to me they don't. Its a matter of logical conclusion. Either they there
is a soul transcending physics, or there is not, if not there cannot be free
will.

The absence of Free Will is not really open to debate, in my view

http://www.kevinaylward.co.uk/replicators/freewill.html
Well, evidently, it's not.

Whether it is or is not correct, has no baring on the fact that none of us
can possible have free will. Its fundermental physics


Kevin Aylward

www.kevinaylward.co.uk
 
K

Kevin Aylward

No. A kick in the balls tells us that we exist. However, we are just
observers. Either we do what we are programmed by genes and memes to do, or
we do what we do due to quantum randomness. Either was we're F&*£ed. There
is just no escape from this conclusion.

Its actually all so simple really.

err....That was a *quote* by...Sherlock Holmes.

Physics does not prove anything, but gives evidence to support its
propositions. Truth can never be proved.

The explanation of the universe as a combination of classical mechanics and
quantum mechanics has extensive support. Fundamentally, its all we have,
well not unless you are a Jesus freak, or some other such numpty.

There *are* no other hypothesis available. The brain is a mass-energy
machine. It obeys the obeys the laws of physics or it doesn't. I believe it
does. The evidence for this is overwhelming, imo.

Kevin Aylward

www.kevinaylward.co.uk
 
K

Kevin Aylward

In essence, yes.

The univese exists. We are mass-energy items in that universe, just going
along with the flow.
Truly a philosphy for libertines, since if everything is
deterministically ordained then one can easily shirk responsibility
for one's actions.

And also if it isn't deterministic we can shirk responsibility. This second
point seems to be missed.

If it is random, then we also have no control either.
The fly in the ointment, however, seems to be that if true randomness
exists, then true determinism can't.

But the key point is that, even with randomness, it still precludes free
will, so its irrelevant whether determinism exists or not, so I don't know
what you mean by fly in the ointment.

I can't really say that it is a "philosophy" as in a non-objective point of
view. The reality, is that physics demands that this is the case. It is the
logical view, but I suppose one can argue that someone taking a logical view
has a logical view philosophy. ahmmmm..

www.kevinaylward.co.uk
 
K

Kevin Aylward

John said:
---
Then you agree that my earlier statement:

"There had to have been, however, something which started it all off."

Is correct?

To clarify, what "started" everything was, if the proposition is correct,
the creation of mass-energy. OK.

However, nothing "started" this "start". It just happened. On its own, for
no reason whatsoever., in my view. I see no reason why there should be a
reason.

You mean Sherlock Holmes wasn't a real person? wow...
The context in which you used it, however, was designed to lend
credence to your "it-just-popped-into-existence" hypothesis, for
which you have no proof.

It's the simplest solution. Apply ochams razor...

Either mass-energy has been here always, or it hasn't.

Cosmological evidence and theory indicts that there was a start to the
universe. Theory (General Relativity) says that the concentrated mass could
not have exited in that same state indefinitely prior. Therefore the
conclusion is that the mass-energy just came into existence. However..there
are other theories...

There is no heaven. What evidence do you have that there is more to the
universe than mass-energy physics? Hint James Randi...

Kevin Aylward
[email protected]
www.kevinaylward.co.uk
 
R

Rich the Philosophizer

No. A kick in the balls tells us that we exist. However, we are just
observers. Either we do what we are programmed by genes and memes to do,
or we do what we do due to quantum randomness. Either was we're F&*£ed.
There is just no escape from this conclusion.

Sure there is! Just undeny Free Will. ;-)

Cheers!
Rich
 
R

Rich the Philosophizer

On a sunny day (Thu, 23 Oct 2008 23:15:31 GMT) it happened Rich Grise


I am not so sure about 'free will'.
I think that idea is more of a religion.

No, in fact, it's almost diametrically opposite to religion. Religions
are invested in denial of Free Will - that's why they want to rule you.

Cheers!
Rich
 
R

Rich the Philosophizer

What I ment with 'religion' is that 'free will' is assumed as a given
fact, just like religions present ideas without proof.

Well, I know mine's a fact, because I can feel it with the certainty
that if I hit my thumb with a hammer, I don't have to consult a book
to know that it HURTS!
There is however now scientific proof against the concept of free will.

Impossible; the Univers is MADE OF Free Will:
http://www.godchannel.com

Cheers!
Rich
 
S

Sjouke Burry

Also, since we don't know what rules govern the Universe, who's to say
it isn't heaven?

Any name,god,fairy,gnome can be used to prove nothing.

Just let fantasy run amok, and start to kill people if they
dont believe you.

Now THAT looks like science...........not.
 
K

Kevin Aylward


Oh dear...
A wall of some sort perhaps? But in every direction? A bubble of
some sort?

Why not?

Unfortunately, non specialist star gazers have this idea that any old
possibility *they* dream up, is a real possibility.

Tell me John, do you really believe that professional phd astronomers and
professional astrophysicists are so completely clueless as to not have
thought of such a trivial obvious potential explanation? This is the issue
on the physics NGs, the "Einstein was wrong" brigade give no credit to
experts that have studied this stuff for 20+ years. Like, as if they
wouldn't also have similar ideas. Its not credible or reasonable.

I can state without hesitation, that the idea of a mass shell enclosing this
universe, does not fit the observations. Its the actual technical details
that matttter, not some ad-hoc well maybe...

Like, do you really believe that the idea of exotic (negative) matter would
be considered if such a simple explanation as a mass shell were valid?
Imagine an infinitely or nearly infinitely dense

No point. Already in contradiction to the known facts.

Kevin Aylward
[email protected]
www.kevinaylward.co.uk
 
K

Kevin Aylward

Apparently not, because what you state below still contradicts the essence
of this point.
Perhaps I made my point badly, since what I meant was that in a truly
deterministic universe there'd be no reason for assuming
responsibility for anything, since it would all be going to happen
the way it would and what would seem to be decisions which one were
making would all really just be illusions since we'd merely be
automatons.

Yes. That point is well understood.

The issue is that randomness doesn't save one from absence of free will.
---


---
Randomness is prohibited by determinism, since it preaches that every
action is preordained, so the only way we can exercise free will is if
randomness exists.
---

My argument (http://www.kevinaylward.co.uk/replicators/freewill.html) is
based on analysing both conditions. Clearly, there is both classical and
quantum approximations acting simultaneously in any situation. Part of a
decision is essentially, predetermined, part is random. *Either* way
prohibits free will, by definition of free will.
---
Randomness is prohibited by determinism, since it preaches that every
action is preordained, so the only way we can exercise free will is if
randomness exists.

Ergo, if you admit that randomness exists then you must accept that
determinism doesn't.

Not at all.

In QM, one can have the probability of a specific event occurring being 0 or
1. Not everything under QM must be random. It depends on the exact nature of
the problem. For example, a measurement of the spin of one electron, can
give a certainty of the spin of another electron.

So. Both randomness and determinism co-exist, according to standard physics.
Then, if you accept that determinism doesn't
exist it follows that free will, which is random, must.

No. That logic makes no sense.

I already explained in that paper. You appear to be saying that if grass is
green, then all that is green is grass.

Free will, essentially by definition, is the ability of an object, an "I" to
make a decision that "I" wants. The fact that an aspect of free will is non
predictability i.e. not determinism, does *not* imply that it must be
random. Free will is the ability to chose for oneself. If the choice is
random, than there is no choice. This is trivially obvious.

Ohh dear...why is this so hard for people to understand. I will a note here
though, is that, when I reasoned this out, it was on my todd, only later did
I discover that exactly the same argument I use against free will, is
already well known and accepted by major philosophers, e.g David Chalmers.


Kevin Aylward
www.kevinaylward.co.uk
 
100% agreed, room acoustics set the scene, so to speak.
Yes, I have used some acoustics programs (running in Linux) but found
those hard to use.
I usually run without equaliser, but equaliser is great to fix some recordings
made from old analog tapes (reduce high frequency hiss), or just for fun make a real
strong bass.
As I stated before, HiFi is no longer my thing, unless perhaps when listening with headphones.
Maybe a few more years and direct brain implants will eliminate the room acoustics factor,
but hopefully after I am gone.
I like music, usually something plays here, either from mp3 (sorry audiophools),
or wave files, or mp2.
It is a background thing, much other noise going on, so fine with me.

As to the intermodulation thing (as discussed before), mp3 is based on
you not being able to hear (Hello Kevin) the small signals in the present
of strong ones.
So you are not likely to hear a weak 1kHz beat between 20kHz and 19 kHz anyways,
as that beat will be much much weaker then those 2 signals.
Now for somebody who cannot hear 20 - and 19 kHz, all that remains may well be 1000Hz,
and the person will hear that.
ONE MORE REASON to use the equaliser and cut above 15 kHz!!!!
Maybe the audiophools just make their own problems.

oops.

I didn't want to get into it. but some speak designs start their HF
rolloff at 10KHz deliberately. Most people can't stand the tsst tsst
tsst sound of many tweeters. Wilson Audio does a similar trick, but
runs a second tweeter that is rear facing and not rolled off. The rear
facing tweeter is easy to verify. The roll off is a bit harder to
verify.

CARA is relatively cheap software and is simple to use. It certainly
verifies diffusion schemes. You can take a corner, and for lack of a
better description, build an inverse corner.
----------
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Hopefully that survives usenet. The effect on reflected sound is
pretty obvious in CARA.
I've also built binomial diffusers and modeled them. Much of the
theory of diffusers was tested using smaller scale devices and radio
waves before computer simulation came along. Now what I don't trust
with CARA is the effect of objects in the middle of the room. Usually,
this is just furniture, but there are some that have tried diffusors
like tall rectangular objects in free space. Then again, maybe CARA
verifies these are junk science.

I used CARA to investigate Bonello criteria The results were
reasonable. Somewhere I have a java apps where I cranked out room
dimensions via brute force to using Bonello's theories.

I was in Dolby Labs theatre. They have a means to mechanically change
the absorption of the walls. The walls are really just acoustically
transparent cloth with devices behind them. Vents are long and skinny
to keep down HVAC noise. They have electronics in their sound system
to add fake HVAC noise because some production companies want to get a
feeling how their movie will do with real noise. If you ever watched
Star Trek Next Generation using high fidelity playback, the effect is
similar.
 
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